The remarkable turn of events, following several years of failed pregnancy attempts, has been revealed in partially redacted emails released under the Freedom of Information Act.

Tian Tian, who arrived in Scotland as part of breeding pair with Yang Guang in 2011, was artificially inseminated for the fifth time late last year.

The decision to go ahead with artificial insemination came after the zoo decided there was now no prospect of Tian Tian and Yang Guang ever mating naturally.

Dcuments released today show that in late July this year Tian Tian’s pregnancy was ‘on track’ and the mother-to-be is ‘doing real well’.

An email, dated July 25 2017, from Iain Valentine, director of giant pandas at the Royal Zoological Society of Scotland (RZSS), to the Scottish Government, stated: “TT doing real well. As things are at the moment, she seems on track but I have shifted possible birth date to around 25th August. Will be able to be a bit more precise in a week’s time.

“So she is about 30 days out now and pregnancy proper has now begun in what we think is a 37 day pregnancy. See or hear from you soon. My best, Iain.”

The email that prompted the revelation was sent earlier that day from the Scottish Government reading: “I was reminded that this is the season when we might be expecting some baby pandas and I know [Scottish Government Official] has been in touch with you about the progress there.”

It was the fifth time Tian Tian has been artificially inseminated and the move sparked renewed criticism from animal rights campaigners, who accused the zoo of being more focused on making money than the panda’s welfare.

Tian Tian had previously given birth to twins in China but all previous attempts to produce a cub at Edinburgh Zoo have failed.